When the same underlying question exists in short-dated and longer-dated versions ('Fed cuts in September' vs 'Fed cuts by year-end'), their prices must stay logically consistent, since anything that happens by September also happened by December. This strategy trades the two against each other when that term structure looks off, for instance if the by-year-end market is priced lower than the sooner one. The edge is the internal inconsistency across time horizons, not a view on the event itself.
Markets on Polymarket where calendar / time-horizon spread is the natural play:
